Cloud IoT Core Sensor Hub
This sample shows how to implement a sensor hub on Android Things that collects sensor data from connected sensors and publish as telemetry events to Google Cloud IoT Core.
The sample showcases a sensor-based device publishing data to Cloud IoT Core. Sensors can be added or removed dynamically, and the device will reconnect automatically to the cloud when power or connectivity is lost.
Sensor data is collected and sent to Cloud IoT Core as telemetry events every 20 seconds by default, and it can be changed from the cloud with device config (cloud to device) messages.
- Android Things compatible board
- Android Studio 2.2+
- 1 bmp280 temperature and pressure
- 1 PIR motion detector sensor or 1 button to simulate the motion detection
- Google Cloud Platform project with Cloud IoT Core enabled
Build and install
On Android Studio, click on the "Run" button. If you prefer to run on the command line, type
./gradlew installDebug adb shell am start com.example.androidthings.sensorhub/.SensorHubActivity
Prepare the device
This sample will create a key pair (private and public) on the device on the first run. The private key will be saved to the Android Keystore, using a secure hardware if one is available. The public key will be printed to logcat and will be available as a file on your external storage location.
You will need the public key to register your device to Cloud IoT Core. Here's how you can fetch it:
adb pull /sdcard/cloud_iot_auth_certificate.pem
or, depending on your platform:
adb -d shell "run-as com.example.androidthings.sensorhub cat /data/user/0/com.example.androidthings.sensorhub/files/cloud_iot_auth_certificate.pem" > cloud_iot_auth_certificate.pem
A new keypair is only generated again when the device is reflashed.
Register the device
cloud_iot_auth_certificate.pem file, you can register your device on
Cloud IoT Core:
gcloud iot devices create <DEVICE_ID> --project=<PROJECT_ID> --region=<CLOUD_REGION> --registry=<REGISTRY_ID> --public-key path=cloud_iot_auth_certificate.pem,type=<CERTIFICATE_TYPE>
DEVICE_ID: your device ID (it can be anything that identifies the device for you)
PROJECT_ID: your Cloud IoT Core project id
CLOUD_REGION: the cloud region for project registry
REGISTRY_ID: the registry name where this device should be registered
CERTIFICATE_TYPE: either "rsa-x509-pem" or "es256-x509-pem" depending on whether your device key algorithm is "RSA" or "EC" (see below)
Configure the device
Now that your device's public key is registered, you can set the device so that it can securely connect to Cloud IoT Core:
adb shell am start -e project_id <PROJECT_ID> -e cloud_region <CLOUD_REGION> -e registry_id <REGISTRY_ID> -e device_id <DEVICE_ID> -e key_algorithm <DEVICE_KEY_ALGORITHM> com.example.androidthings.sensorhub/.SensorHubActivity
Where PROJECT_ID, CLOUD_REGION, REGISTRY_ID and DEVICE_ID must be the corresponding values used to register the device on Cloud IoT Core, and DEVICE_KEY_ALGORITHM must be the standard name of the algorithm to be used for generating the device authentication key. Currently "RSA" and "EC" are supported, and "RSA" is the default in case this argument is not defined.
If the registration and configuration steps were executed successfully, your device will immediately start publishing sensor data to Cloud IoT Core.
You can pipe this data into other Google Cloud services.
If you want to quickly check if messages are being published correctly, you can create a topic subscription (replace SUBSCRIPTION_NAME with any unique name you want):
gcloud pubsub subscriptions create projects/PROJECT_ID/subscriptions/SUBSCRIPTION_NAME --topic=projects/PROJECT_ID/topics/REGISTRY_ID
and then pull messages from this subscription:
gcloud pubsub subscriptions pull --auto-ack projects/PROJECT_ID/subscriptions/SUBSCRIPTION_NAME
Take a look at the Cloud IoT Core documentation to learn how to pipe the data published by your devices into other Google Cloud services.
Copyright 2018 The Android Open Source Project, Inc.
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